Abstract

The optical absorption of graphene strips covered on a multilayer subwavelength grating (MSG) surface is theoretically investigated. The absorption of graphene strips with MSG is enhanced in the wavelength range of 1500 nm to 1600 nm by critical coupling, which is associated with the combined effects of a guided resonance of MSG and its photonic band gap effect. The critical coupling of the graphene strips can be controlled by adjusting the incident angle without changing the structural parameters of MSG. The absorption of graphene strips can also be tuned by varying key parameters, such as grating period, strip width, and incident angle.

This work was partially supported by the National Basic Research Program of China (Grant No. 2010CB327600), the National Natural Science Foundation of China (NSFC) (Grant Nos. 61020106007, 61474008, and 61274044), the Natural Science Foundation of Beijing, China (Grant No. 4132069), the International Science Cooperation Program (Grant No. 2011DFR11010), 111 Project of China (Grant No. B07005), and the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0686). We also would like to thank Dr. W.E.I. Sha, Dr. Y. Xu, and Dr. C.L. Zou for their supports and helpful suggestions.